Endoscopy may be the most common form of minimally invasive surgery. Perhaps the most common form of endoscopy is laparoscopy, which is minimally invasive inspection and surgery inside the abdominal cavity. In a typical laparoscopic surgery, a patient's abdomen is insufflated with gas, and cannula sleeves are passed through small (approximately ½ inch) incisions to provide entry ports for laparoscopic surgical instruments.
As explained in U.S. Pat. No. 6,989,003, entitled, “Obturator and Cannula for a Trocar Adapted for Ease of Insertion and Removal”, a trocar-cannula, commonly referred to as, a trocar, is a surgical device used to obtain access to a body cavity to perform various surgical procedures, such as, laparoscopic surgery or arthroscopic surgery. Typically, a trocar is an elongated, pointed surgical instrument that includes a pointed rod-like device, referred to in the art as an “obturator” that is fitted into a tube-like device that is referred to in the art as a “cannula”. The pointed, sometimes sharply pointed, end of the obturator projects out the end of the cannula and is used to penetrate the outer tissue of the cavity. After the tissue is penetrated and the body cavity, for example, is accessed by the trocar, the obturator is withdrawn from the cavity and the cannula is left in place in the cavity to provide a channel for accessing the cavity. The body cavity can then be accessed by further surgical instruments via the cannula to perform various surgical procedures.
The laparoscopic surgical instruments generally include a laparoscope for viewing the surgical field, and working tools defining end effectors. Typical surgical end effectors include clamps, graspers, scissors, staplers, or needle holders, for example. The working tools are similar to those used in conventional (open) surgery, except that the working end or end effector of each tool is separated from its handle by, e.g., an approximately 12-inch long, extension tube.
To perform surgical procedures, the surgeon passes these working tools or instruments through cannula sleeves to a required internal surgical site and manipulates them from outside the abdomen by sliding them in and out through the cannula sleeves, rotating them in the cannula sleeves, levering (i.e., pivoting) the instruments against the abdominal wall and actuating end effectors on the distal ends of the instruments from outside the abdomen. The instruments pivot around centers defined by the incisions which extend through muscles of the abdominal wall. The surgeon monitors the procedure by means of a television monitor which displays an image of the surgical site via a laparoscopic camera. A laparoscopic camera is also introduced through the abdominal wall and into the surgical site. Similar endoscopic techniques are employed in, e.g., arthroscopy, retroperitoneoscopy, pelviscopy, nephroscopy, cystoscopy, cisternoscopy, sinoscopy, hysteroscopy, urethroscopy and the like.
U.S. Pat. No. 7,155,315, entitled, “Camera Referenced Control in a Minimally Invasive Surgical Apparatus”, describes a minimally invasive telesurgical system for use in surgery to increase a surgeon's dexterity as well as to allow a surgeon to operate on a patient from a remote location. Telesurgery is a general term for surgical systems where the surgeon uses some form of remote control, e.g., a servomechanism, or the like, to manipulate surgical instrument movements rather than directly holding and moving the instruments by hand. In such a telesurgery system, the surgeon is provided with an image of the surgical site at the remote location. While viewing typically a three-dimensional image of the surgical site on a suitable viewer or display, the surgeon performs the surgical procedures on the patient by manipulating master control devices, at the remote location, which control the motion of servomechanically operated instruments.
The servomechanism used for telesurgery will often accept input from two master controllers (one for each of the surgeon's hands), and may include two robotic arms. Operative communication between each master control and an associated arm and instrument assembly is achieved through a control system. The control system includes at least one processor which relays input commands from a master controller to an associated arm and instrument assembly and from the arm and instrument assembly to the associated master controller in the case of, e.g., force feedback.
FIG. 1 is an illustrative drawing showing a known cannula 102 that acts as a conduit for receiving one or more instruments 104 extending through a patient's bodywall 106. The cannula includes a proximal end portion 108 disposed outside the body cavity and a distal end portion 110 that extends within the body cavity. An instrument 104 typically includes an elongated shaft portion 104-1 having an end effector portion 104-2 coupled to a distal working-end thereof. In operation, longitudinal axes of the instrument 104 and the cannula 102 are aligned when the instrument is inserted in the cannula. In some telesurgical systems, a wrist-like mechanism 104-3 is located at the distal end of the instrument between the shaft 104-1 and the end-effector 104-2 to allow rotational movement of the end effector within the body cavity.
Typically, during minimally invasive surgery, a surgeon manipulates the instrument 104 to perform a surgical procedure from a distance, which diminishes the surgeon's ability to use physical touch as a source of feedback during surgery. The surgeon may manipulate an end effector 104-2 disposed at the end of an elongated instrument shaft 104-1 that extends through a cannula 102, for example. As a consequence, a surgeon's may lose the ability to sense the amount of force exerted upon internal body tissue during the procedure. U. S. Patent Application Pub. No. 2011/0178477, entitled, Trocar Device for Passing a Surgical Tool, and N. Zemiti et al., A Force Controlled Laparoscopic Surgical Robot without Distal Force Sensing, Experimental Robotics IX, STAR 21, pages 153-163, Springer-Verlag Berlin Heidelberg 2006, disclose trocar that include sensors used to estimate the force exerted by an elongated instrument upon internal body tissue contacted by a surgical instrument during minimally invasive surgery.